In recent years, a fuel cell car or the like has received attention in which a fuel cell for generating a power by an electrochemical reaction between a fuel gas and an oxidizing gas is used as an energy source.
Such a fuel cell is usually constituted as a fuel cell stack including a cell laminated body in which the required number of cells for generating the power by the electrochemical reaction between the fuel gas and the oxidizing gas are laminated, and an end plate which is arranged outside this cell laminated body in a laminating direction and which imparts a compressive load adjusted with a load adjustment screw to the cell laminated body.
Moreover, in this fuel cell, to uniform the compressive load to the cell laminated body and decrease the fluctuation of the compressive load, a spring module in which a plurality of springs are arranged between plates is interposed between the cell laminated body and the end plate (e.g., see Japanese Patent Application Laid-Open No. 2004-288618).
This spring module is provided with graduations on a side wall vertically disposed on the peripheral edge of one of the plates, and the end position of a side wall vertically disposed on the peripheral edge of the other plate can be read from the graduations to grasp the compressive load to be imparted to the cell laminated body via the spring module.